This invention relates to a manual speed selector of an automatic vehicle transmission whereby the driver can select, by manual operation, a shift stage that he or she wishes to set.
Conventionally, as the shift lever is used to select a running range, e.g., a range D, a range S, and a range L, in an automatic vehicle transmission, a predetermined shift stage is automatically selected according to the vehicle speed and the throttle opening in each range, thereby automatically shifting the transmission. As the shift lever is moved along an I-shaped straight line pattern, a manual valve linked thereto in the hydraulic circuit is moved to selectively operate frictional engagement devices according to the selected range.
However, the shift speed that a driver wishes to select at a given operating state will vary according to the driver's individual preference, and the shift stage automatically selected by the automatic transmission does not always coincide with the shift stage the driver wishes to select. Manual transmissions are advantageous in this respect.
An automatic vehicle transmission has been provided which is arranged to enable manual speed changes and to enable the drive to select a shift stage (refer to Japanese Patent Laid-Open No. 61-157855).
In the above mentioned prior art transmission, an H-shaped shift pattern similar to a pattern for manual shifting is formed so as to be connected to the conventional I-shaped pattern, shift stage positions for manual shifting are set in the H-shaped pattern, and a switch operated by the arrival of the shift lever is provided at each shift stage position. When the shift lever is moved from the I-shaped straight line pattern to one of the positions of the H-shaped pattern, the shift lever is disconnected from the manual valve of the hydraulic circuit, and frictional engagement devices are selected and operated by a signal supplied from the switch provided at the corresponding H-shaped pattern postion to select the corresponding shift stage.
In this type of manual speed selector for automatic vehicle transmissions, however, the shift lever is necessarily passed through the D range position in which automatic shifting is effected, when the shift lever is moved from the I-shaped straight line pattern to the H-shaped pattern. However, a problem in that the driver will feel a difference between the shifting operation and the motion of the vehicle is encountered. For example, if the shift lever is moved from a range N to a first speed position in the H-shaped pattern, the shift therebetween is effected via a first speed in the range D, that is, the first speed is selected after creep-starting. Also, a manual shift for starting in a second speed must be effected via the first speed in the range D and the driver does not feel good responsiveness to manual shifting. In the case of a shift from, for example, a fourth speed to the range N, the shift also involves automatic shifting in the range D, and the same problem is encountered.
In this type of manual speed selector for automatic vehicle transmissions, when the shift lever is moved from a certain shift stage selecting position to effect the next shift stage selection, the previous shift stage is maintained to enable power-on shifting in an intermediate state before a new signal is input. Accordingly, in a case where the driver presses the accelerator pedal while believing that the transmission is in the same state as the neutral of a manual transmission, there is a risk of a friction member being burnt if the previous shift stage is the fourth speed stage or a risk of the vehicle abruptly starting if the previous shift stage is the first speed stage.